Efficient and reliable technologies for the on-site detection
of
illicit drugs are important in drug-facilitated crime investigations.
However, the development of such technologies is challenging. Based
on the synthetic optimization, introducing a boron ester functional
group to the two furanic indicators endows the stimulus-responsive
properties synergistically. The ring-opening reaction of the indicators
in the presence of amine-containing illicit drugs generated well-known
donor–acceptor Stenhouse adducts, accompanied by strong color
changes. A small-size and lightweight laminated sensor was integrated
based on the outstanding ratiometric variations of the two active
furanic indicators. A prototype platform was fabricated equipped with
a circuit control, a mini pump, and a signal processing system. A
user-friendly detection and efficient screening of amine-containing
illicit drugs, including phenethylamines, amphetamines, cathinones,
and tryptamines in the liquid states were conducted. The ratiometric
response of the sensor was linear in the concentration range of 2.1–10.6
μg·mL–1 for methamphetamine·HCl
and methcathinone ·HCl. The detection limits for the two illicit
drugs at the sublevel (ng·mL–1) were found
to be 8.4 and 9.0 ng·mL–1, respectively. Double-blind
field tests and different illicit drugs were evaluated with good screening
capability. Successful trials showed the potential applications of
the developed prototype platform for efficient and on-site analytical
determination.